West syndrome followed by juvenile myoclonic epilepsy: a coincidental occurrence?

Background: West syndrome is an age-dependent epilepsy with onset peak in the first year of life whose aetiology may be symptomatic or cryptogenic. Long-term cognitive and neurological prognosis is usually poor and seizure outcome is also variable. Over the past two decades a few patients with favourable cognitive outcome and with total recovery from seizures were identified among the cryptogenic group suggesting an idiopathic aetiology. Recent research has described two children with idiopathic WS who later developed a childhood absence epilepsy.
Case Presentation: We reviewed the medical records of patients with West syndrome admitted to the our Child Neuropsychiatry Unit in the last 15 years in order to know the clinical evolution of infantile spasms.We report a child with West syndrome with onset at 8 months of age followed by some clusters of bilateral, arrhythmic myoclonic jerks of the upper limbs, mainly on awakening, synchronous with the generalized discharges of 4 Hz spike-wave occurring at 12 years of age and by co-occurrence of a later generalized tonic-clonic seizure at 14 years and four months, both sensitive to Levetiracetam suggesting a juvenile myoclonic epilepsy.
Conclusions: This unusual evolution, never previously reported, suggests that both electroclinical features mentioned above may share some pathophysiological processes genetically determined which produce a susceptibility to seizure and emphasizes that the transition between different age-related epileptic phenotypes may involve also the West syndrome.